[OSM-talk] stop deleting abandoned railroads

Lester Caine lester at lsces.co.uk
Sat Aug 15 11:48:44 UTC 2015

On 15/08/15 12:15, Serge Wroclawski wrote:
>     So who decides what is good data and what is bad data?
> The community as a whole decides what is good and bad data. That starts
> with the local community and moves up to the OSM community as a whole in
> terms of whether or not data belongs in OSM or not.

The problem is one of terminology. Or rather visibility. The data many
of us are looking to use is already in the change logs of the main
database. It is managing the continuity of that older data in
conjunction with later additions that is the problem. An example link
given on this thread showed the break in an old track bed which has been
removed, but currently there is no content for the new road which
follows the line of that track bed. We have lost data which would have
been retained if the relevant section of track bed had been re-tagged as
a road ... and the section that was actually removed by the new highway
was the only piece actually 'deleted'. Just as micro-mapping has little
interest to some users, history is irelevent to others, but that is not
'bad data', but rather data that needs to be managed by a more open
consensus that just 'you can't see it delete it'?

>     And "visibility on the ground" needs nuancing. Are we to remove
>     underground pipelines/power lines?
> If you were able to go underground, then you'd find such data. But if
> you can't- how do you know these lines exist? You probably are using a
> feature that you *can* see without being underground.

That more and more companies are using OSM over google as a base layer
is fact. The question is perhaps should THEIR data be included in the
main database or only accessible as a secondary layer. The points were
underground services are accessed need to be mapped on the main
database, such as station entrances, or storm water outflow pools, so at
what point does third party data become 'mainstream'?

Historic material has exactly the same problem ... that some elements
are 'currently visible' combines with elements that no longer exist is a
a verifiable fact, but either one duplicates the whole lot on an OHM
version of the data, or one simply maintains a little more material in
the main database. The tagging decides what can be seen for a current
rendering rather than snipping out bits which still need to be
maintained for an historic one.

Lester Caine - G8HFL
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